Friday, September 28, 2012

The proposal by USC doctoral student Ouliang Chang, presented last week at the the American Institute of Aeronautics and Astronautics (AIAA) Space 2012 conference, proposes a sci-fi solution to a real-world data overload challenge. NASA controls its interplanetary satellite missions through the Deep Space Network (DSN), a ring of huge satellite dishes in California, Spain and Australia. But the massive amounts of data traffic being sent to NASA is growing at a rate the current set-up can’t handle. Chang has proposed that one way to ease the strain would be to build a supercomputer and accompanying radio dishes on the moon.

This is...such a bad idea I cannot even start. You know what. I will. Though on the official GLXP blog for my team. If there was ever someone that has the background to comment, it'd be me. I think this counts as my He3 for lunar applications.

Monday, September 24, 2012

There is evidence that some microbial life had migrated from the Earth's oceans to land by 2.75 billion years ago, though many scientists believe such land-based life was limited because the ozone layer that shields against ultraviolet radiation did not form until hundreds of millions years later.

But new research from the University of Washington suggests that early microbes might have been widespread on land, producing oxygen and weathering pyrite, an iron sulfide mineral, which released sulfur and molybdenum into the oceans.

"This shows that life didn't just exist in a few little places on land. It was important on a global scale because it was enhancing the flow of sulfate from land into the ocean," said Eva Stüeken, a UW doctoral student in Earth and space sciences.

In turn, the influx of sulfur probably enhanced the spread of life in the oceans, said Stüeken, who is the lead author of a paper presenting the research published Sunday (Sept. 23) in Nature Geoscience. The work also will be part of her doctoral dissertation.

Sulfur could have been released into sea water by other processes, including volcanic activity. But evidence that molybdenum was being released at the same time suggests that both substances were being liberated as bacteria slowly disintegrated continental rocks, she said.

If that is the case, it likely means the land-based microbes were producing oxygen well in advance of what geologists refer to as the "Great Oxidation Event" about 2.4 billion years ago that initiated the oxygen-rich atmosphere that fostered life as we know it.

In fact, the added sulfur might have allowed marine microbes to consume methane, which could have set the stage for atmospheric oxygenation. Before that occurred, it is likely large amounts of oxygen were destroyed by reacting with methane that rose from the ocean into the air.

"It supports the theory that oxygen was being produced for several hundred million years before the Great Oxidation Event. It just took time for it to reach higher concentrations in the atmosphere," Stüeken said.

The research examined data on sulfur levels in 1,194 samples from marine sediment formations dating from before the Cambrian period began about 542 million years ago. The processes by which sulfur can be added or removed are understood well enough to detect biological contributions, the researchers said.

Thursday, September 20, 2012

Genetically, culturally and ethically the Khoe-San have something special to add to this world. The importance of this study is to put the Khoe and San heritage in the right place in history and this research will provide a genetic backdrop for future studies - Mattias Jakobsson.

The largest genomic study ever conducted among Khoe and San groups reveals that these groups from southern Africa are descendants of the earliest diversification event in the history of all humans - some 100 000 years ago, well before the 'out-of-Africa' migration of modern humans.

Some 220 individuals from different regions in southern Africa participated in the research that led to the analysis of around 2.3 million DNA variants per individual – the biggest ever.

The research was conducted by a group of international scientists, including Professor Himla Soodyall from the Human Genomic Diversity and Disease Research Unit in the Health Faculty at the University of the Witwatersrand in Johannesburg.

"The deepest divergence of all living people occurred some 100 000 years ago, well before modern humans migrated out of Africa and about twice as old as the divergences of central African Pygmies and East African hunter-gatherers and from other African groups," says lead author Dr Carina Schlebusch, a Wits University PhD-graduate now conducting post-doctoral research at Uppsala University in Sweden.

Fast-flowing and narrow glaciers have the potential to trigger massive changes in the Antarctic ice sheet and contribute to rapid ice-sheet decay and sea-level rise, a new study has found.

Research results published in the journal Proceedings of the National Academy of Sciences reveal in more detail than ever before how warming waters in the Southern Ocean are connected intimately with the movement of massive ice-sheets deep in the Antarctic interior.

"It has long been known that narrow glaciers on the edge of the Antarctica act as discrete arteries termed ice streams, draining the interior of the ice sheet," says Dr Chris Fogwill, an author of the study and an ARC Future Fellow with the UNSW Climate Change Research Centre.

"However, our results have confirmed recent observations suggesting that ocean warming can trigger increased flow of ice through these narrow corridors. This can cause inland sectors of the ice-sheet - some larger than the state of Victoria - to become thinner and flow faster."

The researchers, led by Dr Nicholas Golledge from Victoria University of Wellington, New Zealand, tested high-resolution model simulations against reconstructions of the Antarctic ice sheet from 20,000 years ago, during the last glacial maximum.

They used a new model, capable of resolving responses to ice-streams and other fine- scale dynamic features that interact over the entire ice sheet. This had not previously been possible with existing models. They then used this data to analyse the effects of a warming ocean over time.

The results showed that while glacier acceleration triggered by ocean warming is relatively localized, the extent of the resultant ice-sheet thinning is far more widespread. This observation is particularly important in light of recently observed dynamic changes at the margins of Antarctica. It also highlighted areas that are more susceptible than others to changes in ocean temperatures.

The glaciers that responded most rapidly to warming oceans were found in the Weddell Sea, the Admundsen Sea, the central Ross Sea and in the Amery Trough.

The finding is important because of the enormous scale and potential impact the Antarctic ice sheets could have on sea-level rise if they shift rapidly, says Fogwill. "To get a sense of the scale, the Antarctic ice sheet is 3km deep - three times the height of the Blue Mountains in many areas - and it extends across an area that is equivalent to the distance between Perth and Sydney.

"Despite its potential impact, Antarctica's effect on future sea level was not fully included in the last IPCC report because there was insufficient information about the behaviour of the ice sheet. This research changes that. This new, high-resolution modelling approach will be critical to improving future predictions of Antarctica's contribution to sea level over the coming century and beyond."

A genetic mutation that occurred thousands of years ago might be the answer to how early humans were able to move from central Africa and across the continent in what has been called "the great expansion," according to new research from Wake Forest Baptist Medical Center.

By analyzing genetic sequence variation patterns in different populations around the world, three teams of scientists from Wake Forest Baptist, Johns Hopkins University School of Medicine and the University of Washington School of Medicine, Seattle, demonstrated that a critical genetic variant arose in a key gene cluster on chromosome 11, known as the fatty acid desaturase cluster or FADS, more than 85,000 years ago. This variation would have allowed early humans to convert plant-based polyunsaturated fatty acids (PUFAs) to brain PUFAs necessary for increased brain size, complexity and function. The FADS cluster plays a critical role in determining how effectively medium-chain PUFAs found in plants are converted to the long-chain PUFAs found in the brain.

This research is published online today in PLOS One.

Archeological and genetic studies suggest that homo sapiens appeared approximately 180,000 years ago, but stayed in one location around bodies of water in central Africa for almost 100,000 years. Senior author Floyd H. "Ski" Chilton, Ph.D., professor of physiology and pharmacology and director of the Center for Botanical Lipids and Inflammatory Disease Prevention at Wake Forest Baptist, and others have hypothesized that this location was critical, in part, because early humans needed large amounts of the long-chain PUFA docosahexaenoic acid (DHA), which is found in shellfish and fish, to support complex brain function.

"This may have kept early humans tethered to the water in central Africa where there was a constant food source of DHA," Chilton said. "There has been considerable debate on how early humans were able to obtain sufficient DHA necessary to maintain brain size and complexity. It's amazing to think we may have uncovered the region of genetic variation that arose about the time that early humans moved out of this central region in what has been called the 'great expansion.'"

Once this trait arose, the study shows that it was under intense selective pressure and thus rapidly spread throughout the population of the entire African continent. "The power of genetics continually impresses me, and I find it remarkable that we can make inferences about things that happened tens of thousands of years ago by studying patterns of genetic variation that exist in contemporary populations," said Joshua M. Akey, Ph.D., lead scientist at the University of Washington.

This conversion meant that early humans didn't have to rely on just one food source, fish, for brain growth and development. This may have been particularly important because the genetic variant arose before organized hunting and fishing could have provided more reliable sources of long-chain PUFAs, Akey said.

To investigate the evolutionary forces shaping patterns of variation in the FADS gene cluster in geographically diverse populations, the researchers analyzed 1,092 individuals representing 15 different human populations that were sequenced as part of the 1000 Genome Project and 1,043 individuals from 52 populations from the Human Genome Diversity Panel database. They focused on the FADS cluster because they knew those genes code for the enzymatic steps in long-chain PUFA synthesis that are the least efficient.

Chilton said the findings were possible because of the collaboration of internationally recognized scientists from three distinct and diverse disciplines – fatty acid biochemistry (Wake Forest Baptist), statistical genetics (Johns Hopkins) and population genetics (University of Washington). This new information builds on Chilton's 2011 research findings published in BMC Genetics that showed how people of African descent have a much higher frequency of the gene variants that convert plant-based medium-chain omega-6 PUFAs found in cooking oils and processed foods to long-chain PUFAs that cause inflammation. Compared to Caucasians, African Americans in the United States have much higher rates of hypertension, type 2 diabetes, stroke, coronary heart disease and certain types of cancer. "The current observation provides another important clue as to why diverse racial and ethnic populations likely respond differently to the modern western diet," Chilton said.

Wednesday, September 19, 2012

The frozen cap of the Arctic Ocean appears to have reached its annual summertime minimum extent and broken a new record low on Sept. 16, the National Snow and Ice Data Center (NSIDC) has reported. Analysis of satellite data by NASA and the NASA-supported NSIDC at the University of Colorado in Boulder showed that the sea ice extent shrunk to 1.32 million square miles (3.41 million square kilometers).

The new record minimum measures almost 300,000 square miles less than the previous lowest extent in the satellite record, set in mid-September 2007, of 1.61 million square miles (4.17 million square kilometers). For comparison, the state of Texas measures around 268,600 square miles.

NSIDC cautioned that, although Sept. 16 seems to be the annual minimum, there's still time for winds to change and compact the ice floes, potentially reducing the sea ice extent further. NASA and NSIDC will release a complete analysis of the 2012 melt season next month, once all data for September are available.

Arctic sea ice cover naturally grows during the dark Arctic winters and retreats when the sun re-appears in the spring. But the sea ice minimum summertime extent, which is normally reached in September, has been decreasing over the last three decades as Arctic ocean and air temperatures have increased. This year's minimum extent is approximately half the size of the average extent from 1979 to 2000. This year's minimum extent also marks the first time Arctic sea ice has dipped below 4 million square kilometers.

"Climate models have predicted a retreat of the Arctic sea ice; but the actual retreat has proven to be much more rapid than the predictions," said Claire Parkinson, a climate scientist at NASA Goddard Space Flight Center, Greenbelt, Md. "There continues to be considerable inter-annual variability in the sea ice cover, but the long-term retreat is quite apparent."

The thickness of the ice cover is also in decline.

"The core of the ice cap is the perennial ice, which normally survived the summer because it was so thick", said Joey Comiso, senior scientist with NASA Goddard. "But because it's been thinning year after year, it has now become vulnerable to melt".

The disappearing older ice gets replaced in winter with thinner seasonal ice that usually melts completely in the summer.

30 minute loiter time? The article says it has a max speed of 60 mph (96km/h). I doubt that it has a 30 minute loiter with 60 mph the entire time. Even so, if its doing 20 mph for 30 minutes, you have infantry with a range of 10 miles. Even more interesting would be if you could pack the launch tubes into something like a M113 as vertical launch tubes. Esp if they could have a shape charge version of the warhead. I wonder how many they could pack in it?

When a huge meteor collided with Earth about 2.5 million years ago and fell into the southern Pacific Ocean it not only could have generated a massive tsunami but also may have plunged the world into the Ice Ages, a new study suggests.

A team of Australian researchers says that because the Eltanin meteor – which was up to two kilometres across - crashed into deep water, most scientists have not adequately considered either its potential for immediate catastrophic impacts on coastlines around the Pacific rim or its capacity to destabilise the entire planet's climate system.

"This is the only known deep-ocean impact event on the planet and it's largely been forgotten because there's no obvious giant crater to investigate, as there would have been if it had hit a landmass," says Professor James Goff, lead author of a forthcoming paper in the Journal of Quaternary Science. Goff is co-director of UNSW's Australia-Pacific Tsunami Research Centre and Natural Hazards Research Laboratory.

"But consider that we're talking about something the size of a small mountain crashing at very high speed into very deep ocean, between Chile and Antarctica. Unlike a land impact, where the energy of the collision is largely absorbed locally, this would have generated an incredible splash with waves literally hundreds of metres high near the impact site.

"Some modelling suggests that the ensuing mega-tsunami could have been unimaginably large – sweeping across vast areas of the Pacific and engulfing coastlines far inland. But it also would have ejected massive amounts of water vapour, sulphur and dust up into the stratosphere. "The tsunami alone would have been devastating enough in the short term, but all that material shot so high into the atmosphere could have been enough to dim the sun and dramatically reduce surface temperatures. Earth was already in a gradual cooling phase, so this might have been enough to rapidly accelerate and accentuate the process and kick start the Ice Ages."

In the paper, Goff and colleagues from UNSW and the Australian Nuclear Science and Technology Organisation, note that geologists and climatologists have interpreted geological deposits in Chile, Antarctica, Australia, and elsewhere as evidence of climatic change, marking the start of the Quaternary period. An alternative interpretation is that some or all of these deposits may be the result of mega-tsunami inundation, the study suggests.

"There's no doubt the world was already cooling through the mid and late Pliocene," says co-author Professor Mike Archer. "What we're suggesting is that the Eltanin impact may have rammed this slow-moving change forward in an instant - hurtling the world into the cycle of glaciations that characterized the next 2.5 million years and triggered our own evolution as a species.

"As a 'cene' changer - that is, from the Pliocene to Pleistocene - Eltanin may have been overall as significant as the meteor that took out the non-flying dinosaurs 65 million years ago. We're urging our colleagues to carefully reconsider conventional interpretations of the sediments we're flagging and consider whether these could be instead the result of a mega-tsunami triggered by a meteor."

I suspect that the impact needs to be better constrained for this to be taken past the point of a hypothesis. I find a number of places (like the UCSC image above) that would place the impact at different time periods which would kill the causality.

A team of Australian researchers, led by University of Melbourne has developed a genetic test that is able to predict the risk of developing Autism Spectrum Disorder, ASD.

Lead researcher Professor Stan Skafidas, Director of the Centre for Neural Engineering at the University of Melbourne said the test could be used to assess the risk for developing the disorder.

"This test could assist in the early detection of the condition in babies and children and help in the early management of those who become diagnosed," he said.

"It would be particularly relevant for families who have a history of Autism or related conditions such as Asperger's Syndrome," he said.

Autism affects around one in 150 births and is characterized by abnormal social interaction, impaired communication and repetitive behaviours.

The test correctly predicted ASD with more than 70 per cent accuracy in people of central European descent. Ongoing validation tests are continuing including the development of accurate testing for other ethnic groups.

Clinical neuropsychologist, Dr Renee Testa from the University of Melbourne and Monash University, said the test would allow clinicians to provide early interventions that may reduce behavioural and cognitive difficulties that children and adults with ASD experience.

"Early identification of risk means we can provide interventions to improve overall functioning for those affected, including families," she said.

A genetic cause has been long sought with many genes implicated in the condition, but no single gene has been adequate for determining risk.

Using US data from 3,346 individuals with ASD and 4,165 of their relatives from Autism Genetic Resource Exchange (AGRE) and Simons Foundation Autism Research Initiative (SFARI), the researchers identified 237 genetic markers (SNPs) in 146 genes and related cellular pathways that either contribute to or protect an individual from developing ASD.

Senior author Professor Christos Pantelis of the Melbourne Neuropsychiatry Centre at the University of Melbourne and Melbourne Health said the discovery of the combination of contributing and protective gene markers and their interaction had helped to develop a very promising predictive ASD test.

The test is based on measuring both genetic markers of risk and protection for ASD. The risk markers increase the score on the genetic test, while the protective markers decrease the score. The higher the overall score, the higher the individual risk.

Wednesday, September 12, 2012

At first glance, the center of the Milky Way seems like a very inhospitable place to try to form a planet. Stars crowd each other as they whiz through space like cars on a rush-hour freeway. Supernova explosions blast out shock waves and bathe the region in intense radiation. Powerful gravitational forces from a supermassive black hole twist and warp the fabric of space itself.

Yet new research by astronomers at the Harvard-Smithsonian Center for Astrophysics shows that planets still can form in this cosmic maelstrom. For proof, they point to the recent discovery of a cloud of hydrogen and helium plunging toward the galactic center. They argue that this cloud represents the shredded remains of a planet-forming disk orbiting an unseen star.

"This unfortunate star got tossed toward the central black hole. Now it's on the ride of its life, and while it will survive the encounter, its protoplanetary disk won't be so lucky," said lead author Ruth Murray-Clay of the CfA. The results are appearing in the journal Nature.

The cloud in question was discovered last year by a team of astronomers using the Very Large Telescope in Chile. They speculated that it formed when gas streaming from two nearby stars collided, like windblown sand gathering into a dune.

Murray-Clay and co-author Avi Loeb propose a different explanation. Newborn stars retain a surrounding disk of gas and dust for millions of years. If one such star dived toward our galaxy's central black hole, radiation and gravitational tides would rip apart its disk in a matter of years.

They also identify the likely source of the stray star - a ring of stars known to orbit the galactic center at a distance of about one-tenth of a light-year. Astronomers have detected dozens of young, bright O-type stars in this ring, which suggests that hundreds of fainter Sun-like stars also exist there. Interactions between the stars could fling one inward along with its accompanying disk.

Although this protoplanetary disk is being destroyed, the stars that remain in the ring can hold onto their disks. Therefore, they may form planets despite their hostile surroundings.

As the star continues its plunge over the next year, more and more of the disk's outer material will be torn away, leaving only a dense core. The stripped gas will swirl down into the maw of the black hole. Friction will heat it to high enough temperatures that it will glow in X-rays.

Friday, September 07, 2012

Deforestation can have a significant effect on tropical rainfall, new research confirms. The findings have potentially devastating impacts for people living in and near the Amazon and Congo forests.

A team from the University of Leeds and the NERC Centre for Ecology & Hydrology found that for the majority of the Earth's tropical land surface, air passing over extensive forests produces at least twice as much rain as air passing over little vegetation. In some cases these forests increased rainfall thousands of kilometres away.

By combining observational data with predictions of future deforestation, the researchers estimate that destruction of tropical forests would reduce rain across the Amazon basin by up to a fifth (21 per cent) in the dry season by 2050. The study is published today in Nature.

Lead author Dr Dominick Spracklen from the School of Earth and Environment at the University of Leeds said: "We were surprised to find that this effect occurs strongly across more than half of the tropics. We found that the Amazon and Congo forests maintain rainfall over the periphery of the forest basins - regions where large numbers of people live and rely on rainfall for their livelihoods.

"Our study implies that deforestation of the Amazon and Congo forests could have catastrophic consequences for the people living thousands of kilometres away in surrounding countries."

Scientists have debated whether vegetation increases rainfall for hundreds of years. It is well established that plants put moisture back in the air through their leaves by a process known as evapotranspiration, but the quantity and geographical reach of rainfall generated by large forests has – until now – been unclear. While there is plenty of anecdotal evidence that forests significantly increase rainfall, until now there has been a lack of observational evidence.

The team used newly available NASA satellite observations of rainfall and vegetation, along with a model which predicts atmospheric wind flow patterns, to explore the impact of the Earth's tropical forests.

"We looked at what had been happening to the air over previous days – where it came from and how much forest it had travelled over," Dr Spracklen said.

To understand the relationship in detail, they investigated the journey of air masses arriving over different parts of the forest, to see the cumulative amount of leaf cover the air had moved over during the previous ten days, not just the amount of vegetation it was over when it rained. This showed that the more vegetation the air had travelled over, the more moisture it carried and more rain was produced.

Dr Stephen Arnold from the University of Leeds, a co-author on the paper, said: "The observations show that to understand how forests impact rainfall, we need to account for how air has interacted with vegetation during its journey through the atmosphere often over thousands of kilometres. This has significant implications for how policy makers should consider the environmental impacts of deforestation, since its effects on rainfall patterns may be felt not only locally, but on a continental scale.

Wednesday, September 05, 2012

The most-studied mass extinction in Earth history happened 65 million years ago and is widely thought to have wiped out the dinosaurs. New University of Washington research indicates that a separate extinction came shortly before that, triggered by volcanic eruptions that warmed the planet and killed life on the ocean floor.

The well-known second event is believed to have been triggered by an asteroid at least 6 miles in diameter slamming into Mexico's Yucatán Peninsula. But new evidence shows that by the time of the asteroid impact, life on the seafloor – mostly species of clams and snails – was already perishing because of the effects of huge volcanic eruptions on the Deccan Plateau in what is now India.

"The eruptions started 300,000 to 200,000 years before the impact, and they may have lasted 100,000 years," said Thomas Tobin, a UW doctoral student in Earth and space sciences.

The eruptions would have filled the atmosphere with fine particles, called aerosols, that initially cooled the planet but, more importantly, they also would have spewed carbon dioxide and other greenhouse gases to produce long-term warming that led to the first of the two mass extinctions.

"The aerosols are active on a year to 10-year time scale, while the carbon dioxide has effects on a scale of hundreds to tens of thousands of years," Tobin said.

During the earlier extinction it was primarily life on the ocean floor that died, in contrast to the later extinction triggered by the asteroid impact, which appeared to kill many more free-swimming species.

"The species in the first event are extinct but the groups are all recognizable things you could find around on a beach today," he said.

Tobin is the lead author of a paper in the journal Palaeogeography, Palaeoclimatology, Palaeoecology that documents results of research conducted in a fossil-rich area on Seymour Island, off the Antarctic Peninsula.

That particular area has very thick sediment deposits and, for a given interval of time, might contain 10 times more sediment as the well-known Hell Creek Formation in Montana. That means scientists have much greater detail as they try to determine what was happening at the time, Tobin said.

The researchers took small surface core samples from rocks and fossils in the Antarctic sediment and used a method called magnetostratigraphy, employing known changes over time in Earth's magnetic field to determine when the fossils were deposited. The thicker sediment allowed dating to be done more precisely.

"I think the evidence we have from this location is indicative of two separate events, and also indicates that warming took place," Tobin said.

I have been reading this paper for a bit now and had been planning on doing a write up for some time. I am going to make a couple very quick comments here, but they ought to be expanded on in a dedicated post.

First, good for Tobin for looking for different signatures for the possible different extinctions! I don't know ANYONE who has suggested doing that! ;)

Second, its a bit of caution. He has a single site that suggests this. The evidence definitely supports some sort of information to this effect at that site. However, part of what is so, forgive me, powerful about the Chicxulub Impact theory is that its not just a site that supports the bollide kill theory, but many. There are several possible scenarios that could produce what Tobin et al find. If you had the a site that contained dead zones found in the Gulf after the oil disaster (and somewhat before) without any other locales, you might draw the conclusions that the Gulf was experiencing a benthic extinction. More sites to support the claim ought to be found for this to be well supported.